Epoxy Resin Coatings

Description

Epoxy resin coatings that contain a high number of epoxy groups in their composition are collectively known as epoxy paints. Epoxy resin is a class of macromolecular prepolymer containing two or more epoxy groups in the molecular structure and is an important thermosetting resin. Epoxy resin includes both oligomers of epoxy groups and low molecular compounds containing epoxy groups. Epoxy resins are widely used as resin matrix for adhesives, coatings and composites in the fields of water conservancy, transport, machinery, electronics, home appliances, automotive and aerospace.

Classification methods of epoxy resin coatings

1.Classified by construction method

Spray coatings, roll coatings, flow coatings, dip coatings, electrostatic coatings, electrophoresis coatings, powder flow coatings, and brush coatings.

2. Classified by application

Architectural coatings, automotive coatings, marine coatings, wood coatings, machine materials, sign coatings, electrical insulation coatings, conductive and semiconductor coatings, chemical-resistant coatings, corrosion-resistant coatings, heat-resistant coatings, fire-resistant coatings, show coatings, lubricating coatings, food can coatings and flame-retardant coatings.

3. Classified by curing method

Self-drying coatings with one-component or two-components or multi-components liquid coatings, baking coatings with one-component and two-components solid or liquid coatings, radiation curing coatings.

4. Classified by curing method

Amine-curing coatings, anhydride (or acid) curing coatings, and synthetic resin-based coatings.

5. Classified by coating state

Solvent-based coatings, solvent-free (liquid and solid) coatings, and (water emulsified and water-soluble) coatings.

Advantages of epoxy resin coatings

High mechanical properties

Epoxy resin has strong cohesion and dense molecular structure, so its mechanical properties are higher than general-purpose thermosetting resins such as phenolic resin and unsaturated polyvinyl acetate.

Strong adhesion

Epoxy resin curing system contains a great activity of epoxy, light base and ether bond, amine bond, vinegar bond and other polar groups, giving epoxy curing material excellent adhesion.

Small curing shrinkage

Generally its curing shrinkage is1%-2%. It is one of the varieties with the smallest curing shrinkage in thermosetting resin. Linear expansion coefficient is also very small. So the volume change after curing is not big.

Excellent electrical insulation

Epoxy resin is one of the best performance varieties among thermosetting resins.

Good workmanship

Epoxy resin curing basically does not produce low molecular volatiles, so can be low-pressure molding or contact pressure molding. Can cooperate with various curing agents to manufacture many types of environmentally friendly coatings.

Good stability and excellent resistance to chemicals

Epoxy resin without alkali, salt and other impurities is not easy to deteriorate. Epoxy curing material has excellent chemical stability. Its resistance to alkali, acid, salt and other media corrosion performance is superior, so epoxy resins are used as anti-corrosion primer. And due to its cured material is a three-dimensional mesh structure, it is resistant to oil and other impregnation, so it is also used for lining the inner wall of the oil tank.

Good heat resistance

Epoxy curing material heat resistance is generally 80-100°C. Epoxy resin heat-resistant varieties can withstand temperatures to 200°C or higher.

Disadvantages of epoxy resin coatings

1. Poor weather resistance, and easy to chalk. Epoxy resin generally contains aromatic ether bonds, cured by sunlight is easy to degrade the chain, so the usual bisphenol A epoxy resin cured material in the outdoor sun, easy to lose luster, and gradually chalking, so it is not suitable for use as outdoor topcoat.

2. Epoxy resin has hydroxyl group, if not handled properly, the water resistance of the coating film will be poor.

3. When epoxy resin is cured, the coating is hard and the primer and putty made of it are not easy to be sanded.

Application

Epoxy resin used as coating accounts for about 35% of the total epoxy resin, the main applications are anti-corrosion epoxy coatings, marine coatings, electrical insulation epoxy resin coatings, food cans interior coatings, water-based coatings, underground facilities protective coatings and so on.

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